Control operating



June 18, 1935. J, T N|CH0L$ 2,005,157 CONTROL OPERATING Filed Nov. 14, 1932 .fo/vw 7T N/CHOLS Patented June l18, 1935 "UNITED STAT-ss eATENT oFFIcl'f" CONTROL OPERATING John T. Nichols, Pittsburgh, Pa.

Application November 14, 1932, Serial No. 642,671

1 Claim.

This invention relates to devices automatically yoperating controls to maintain conditions affected 'thereby within determined ranges. One object is v.to provide a device which will operate a control to hunt a resting point best suited for the main'- tenance of such a range. Other objects may be inferred from the following exemplary disclosure of the invention applied to a furnace fuel valve to maintain a determined range of furnace temperatures.

Referring to the drawing:

t Figure l is a schematic drawing of the invenion.

Figure 2 is a detail from the first ligure.

A furnace fuel control valve I is operated by a reversing electric motor 2 through a gear reduction unit 3. The motor 2 is controlled by a pyrometric switch which includes a movable contact 4 and fixed contacts 5 and 6. Thesecontacts are energized by power lines 'I and 8, line 'I being connected to the right hand contact 5 through a solenoid 9 and to the left hand contact through a solenoid I0, and the line 8 to the central movable contact 4.

This pyrometric switch is arranged for operation when a range of temperatures is exceeded by a furnace whose fuel supply is controlled by the valve I. When the temperatures drop below this range the movable contact 4 closes with the right hand fixed contact 5, and when the temperatures rise above this range this movable Contact closes with the left hand fixed contact 6. The solenoids 9 and Ii) are thereby selectively energized according to the conditions in the furnace. "Ihese solenoids each operate a bank of switches associated therewith, by respective attraction of the armatures ElEL and Illa.

When the temperature rises above the range the contacts 4 and 6 of the pyrometric switch close so that the solenoid I is energized and its operating armature attracted. This closes a contact I I and energizes the motor 2 so that it operates to drive the valve I in a. closing direction. This circuit is effected through the lines 1 and 8, the line 8 being then connected through the line I Ia to drive the motor 2 in this direction.

The operating shaft I2L of the valve I extends through and beyond the gear reduction unit 3 and carries a brush contactor I2 energized by the line 8 through a suitable collector. This brush contactor cooperates with a commutator member I3 driven by a motor I4 through a gear reduction unit I at a much slower speed than the valve operates.

A contact I6 closes simultaneously with the contact II and energizes this motor I4 to drive the commutator element I3 in the same direction the brush contactor I2 is moved. This brush contacter moves with the control valve I, as it is carried directly by the latters operating shaft. This commutator element carries separated arcuate contacting segments I3=1 and ISl0 which communicate with lines Il and I8 through'suitable collector elements.

As the furnaces temperature is brought within the desired range ther contacts 4 and B break the circuit to the solenoid Il] and the armature Ida is released. This opens the contacts II and f I6 andvstops the motors 2 and I4. The releasal of this armature also closes contacts IS and 2B so that a circuit is established'to the motor 2 through the lines ISa, 26a, closed switches 2l and 22, lines I'I and |53, commutator segments I3zu and I3b, brush I2 and line 8. As the brush I2 is rotated faster than the cominutator elements I3 it will be on the latters segment I3a so that the motor 2 is circuited for reverse operation tov that of its operation by the pyrometric switch. This turns the valve in an opening direction until the brush I2 is brought to the dead spot between the commutators segments Ita and I3b.

When the temperature falls the contacts 4 and 5 of the pyrometric switch are closed so that the solenoid 9 is energized and its operating armature attracted. This closes contacts 23 and 2d and opens 2i and 22 and operates the motor to open the valve I. This is circuited similarly to the switches associated with the contacts 4 and 5 except that the two motors are reversed. When y the temperature isagain within the desired range the contacts i and 5 open and the solenoid 9 de" energized, thus bringing the motor 2 under the control of these commutator and brush elements. In this case, however, the brush contacter I2 will be on the segment Ib of the commutator element so that the motor 2 is operated in a valve closing direction. As soon as the brush contactor reaches the commutators dead spot the motor 2 stops and the valve I rests.

If a pyrometric switch is used to control a furnace valve it is necessary to arbitrarily retum the valve to a resting position when not under this switehs control. If this point is set, it is impossible to compensate for varying furnace loads and the motor controlling the valve must be constantly in motion. By the use of the control here disclosed the valve automatically hunts a resting position which compensates for Varying loads in the furnace.

The specific example shown and described is in accordance with the patent statutes and is not for the purpose of limiting the invention specifically thereto. For instance, the brush contactor and commutator elements may be substituted by cam-actuated switch elements, etc., and the circuits varied considerably without departing from the inventive idea.

I claim:

The combination of a. control, a reversing elec- 10 tric motor driving said` control, means for connecting said motor when the extremes of a range of conditions affected by said control are exceeded, and means including cooperative elements respectively moving at the same and reduced speeds as said controller for reversely connecting said motor when disconnected by said rst means, said elements being constructed-and arranged to disconnect said motor when they are respectively moved to determined mutual positions.

, JOHN T. NICHOLS. 

